It appears that Activison isn't quite done with the TNMT brand just yet, as achievements for an unannounced "mature" Teenage Mutant Ninja Turtles game have appeared online.
According to the listing on XboxAchievements.com and an Australian Classification dated November 2015, the new Turtles game will called Teenage Mutant Ninja Turtles: Mutants in Manhattan and will be developed by Platinum Games with an "M for Mature" rating.
There's a total of 50 achievements listed for Mutants in Manhattan and from the list we are able to have a guess at what we can expect. As well as online play, skateboarding and the ability to switch between Turtles on the fly, several location and traversal achievements strongly suggest that Mutants in Manhattan may feature an open-world similar to the Batman Arkham series - an open map littered with explorable buildings, areas and stages.
We will learn more details once the game is officially announced, of course.
Activison's last TMNT game, Teenage Mutant Ninja Turtles: Out of the Shadows, wasn't good at all, but the idea of a mature open-world Turtles game by Platinum Games has got us all a little excited.